agent-loop: projection, recovery, compaction into the crate (phase 3)

The session handler is now a thin shell: three entry points in
kernel_turn.rs (run_kernel_turn / recover_turn / resolve_pending_call)
and the ChatSessionHandler. Everything that shaped a Value — projection,
recovery, compaction mechanics, the LLM loop, message building — lives
in agent-loop or behind a loop_adapters trait.

agent-loop:
- projection/ (mod + media): stored history -> wire messages, the one
  place provider divergence lives; well-formedness contract, DTL
  injections (append-only), media parts. LinearAssembler is now a
  Projection + ProjectionHooks config, not its own implementation
- recovery.rs: reap interrupted batches -> resolve the deepest frame's
  non-terminal calls (Running by policy + RestartHint, AwaitingHuman
  re-asked) -> un-wedge finished children -> cascade up, every frame on
  its own agent (B3)
- compaction.rs: split point (never assistant+tool group), transcript,
  SUMMARY_PREFIX/preamble/template, the no-tools model call, summary row
- manager: resolve_pending (gate skipped, real ToolContext, then
  continue incl. sub-agent); start_loop used by recovery; LiveInput
- delegate: AsyncExecutor + StoreSink for mode:async (durable cron row,
  result delivered back into the parent conversation)
- kernel/context/store: support the above (TurnScope via Extensions,
  frame lookups, aligned result-text semantics)

skald-core:
- loop_adapters: UserLoopRuntime (D12 - one LoopManager per user),
  TurnScope (per-turn state in the Extensions type-map; no scope is
  denied), projection_cfg/media_source/tool_digest (Skald's projection
  knobs without owning projection code), async_task (CronExecutor +
  DurableSink)
- session/handler: stripped to mod.rs + kernel_turn.rs + config.rs +
  interface_tools.rs + media.rs; deleted agent_dispatch, approval,
  dispatch, emitter, gate, llm_call, llm_loop, message_builder,
  messages, outcome, resume
- compactor.rs: policy only (threshold, model pick, CompactionEvent);
  mechanics are the crate's

CLAUDE.md updated (recovery, compaction, sub-agents, approval gate,
projection sections now describe the crate-owned flow).

crates/skald-core/src/loop_adapters/mod.rs

@@ -1,6 +1,6 @@
-//! Skald-side adapters implementing the `agent-loop` trait surface over the
-//! existing infrastructure (blueprint §14 phase 1). **Unused by the current
-//! loop** — they compile and are unit-tested here, and get wired in phase 2.
+//! Skald-side adapters implementing the `agent-loop` trait surface: everything
+//! the library asks a host for, answered the way Skald does it. The loop itself
+//! — rounds, projection, delegation, recovery, compaction — is the crate's.
 //!
 //! - [`history::SqliteHistory`] — `HistoryStore` over the existing
 //!   `chat_sessions_stack` / `chat_history` / `chat_llm_tools` / `chat_summaries`
@@ -14,17 +14,35 @@
 //!   `AgentRunConfig::all_tool_defs`), plus the core-api→agent-loop tool bridge.
 //! - [`activation`] — `ActivationSource` + `ToolActivator` over the
 //!   `activated_tools` table and the MCP provider (D15).
+//! - [`projection_cfg`] — the wire knobs Skald's models need, handed to the
+//!   library's projection engine, plus the assembler every turn runs on.
+//!   Skald owns no projection code: [`media_source`] authorizes which files may
+//!   be inlined (§6 containment) and [`tool_digest`] condenses an over-long
+//!   tool result — the library does the shaping.
+//! - [`async_task`] — `execute_task mode=async` as a durable cron job, and the
+//!   delivery of its result back into the parent conversation (§7.2).
+//! - [`runtime::UserLoopRuntime`] — the one `LoopManager` per user (D12) these
+//!   are all assembled into, plus the per-turn parameters.
 
 pub mod activation;
-pub mod assembler;
+pub mod async_task;
 pub mod builtins;
 pub mod catalog;
 pub mod gate;
 pub mod history;
 pub mod hooks;
 pub mod live_input;
+pub mod media_source;
 pub mod preview;
+#[cfg(test)]
+mod projection_snapshots;
+pub mod scope;
+pub mod projection_cfg;
+pub mod runtime;
 pub mod selector;
 pub mod system;
+#[cfg(test)]
+mod testkit;
+pub mod tool_digest;
 pub mod toolset;
 pub mod translate;